Buying a camera

I am planning to buy a digital SLR camera sometime in the next few months and I need recommendations. I've read through some review sites and based on that, I'm thinking about a Canon Rebel XS or XSi or a Nikon D60, D3000, or D5000. I'm looking for something in the $500-$650 range for the camera and standard lens, and ideally for a telephoto lens also (I'm pushing my luck a bit there, but Amazon has a few packages like that).

I wish I knew a little more about the technicalities of digital photography. I'm doing some reading online, but it's difficult to keep all the terms straight. I've read that you're supposed to think about what you take pictures of, and for me that's mostly landscapes, macro photography of nature, and documenting events (portraits of people standing in front of something). However, I've been saying I'd upgrade to digital SLR on the occasion of either going on a major trip or having a baby, and we're planning a trip to Scandinavia this spring. Thus, I'm planning to use this camera to take pictures of interesting things I see while traveling, and later on when we have kids I'll use it to take pictures of them.

From what I've read, it seems like the cameras in the category I'm looking at (bottom of the price range for dSLRs, good for someone like me who is not a professional photographer and just wants better picture quality than a point-and-shoot can provide) are all about equal in terms of photo quality. So how do I figure out which one to buy?